Recent clinical research and case studies have indicated that the presence of sexual impotence among males who have recently recovered from myocardial infarction may range between 30% and 60%. Treatment methods have been recommended for these patients, without adequate knowledge of the type or etiology of impotence. A technology based upon both psychological, waking state physiological, and sleeping state physiological assessments has been developed which will permit separation of vascular-organic, neurological-organic, and psychogenic etiologies in impotent males. Also, the technology for automated detection of heart arrhythmia has been developed. Using a longitudinal control group design, we propose to (1) determine the incidence of and etiology of impotence in a group of post myocardial infarction males based upon hormone, psychometric and physiological indicies, (2) relate cardiac function (arrhythmia and heart rate) to sleep stages, nocturnal tumescence episodes and six month post myocardial infarction recovery, (3) determine the effects of 6 months of post MI recovery on sexual functioning as assessed by psychological, physiological, and hormonal measures. The proposed investigation is the first comprehensiv study of the impactof acute myocardial infarction on cardiac and sexual function.